Cryptanalysis of Certificateless Signcryption Schemes and an Efficient Construction without Pairing

Certificateless aggregate signcryption: Security model and a concrete construction secure in the random oracle model

Signcryption is a cryptographic technique that provides both confidentiality and authenticity of data during public transmission in many modern applications like Internet -of -Things (IoT), Wireless Sensor Networks (WSNs) etc. The functionalities of encryption and Signature can achieve simultaneously through the signcryption with lower computational cost and communication overheads than those of traditional sign-then-encrypt approach. Many signcryption schemes have been constructed by various researchers in different cryptographic frameworks. Certificateless cryptography is one of the recent public key cryptography which eliminates the key escrow problem and complex certificate management problemsin identity based cryptography and traditional public key cryptography respectively. Providing the security and efficiency in many modern applications including IoT and WSNs is a crucial task. In this paper, we proposed new signcryption scheme in certificateless cryptography. This scheme supports the property of public verifiability and is secure against various types of adversaries in the random oracle model with the assumption that the Computational Diffie-Hellman Problem (CDHP) and the Elliptic Curve Discrete Logarithmic Problems (ECDLP) are hard. Due to pairing-free environment the proposed scheme is computationally more efficient than the existing public verifiable signcryption schemes.

Signcryption can realize encryption and signature simultaneously with lower computational costs and communicational overheads than those of the traditional sign-then-encrypt approach. Certificateless cryptosystem solves the key escrow problem in the identity-based cryptosystem and simplifies the public key management in the traditional public key cryptosystem. There have been some certificateless signcryption schemes proposed in the standard model up to now, but all of them are just proposed in a weaker Type I security model, which is weaker than the original security model of Barbosa and Farshim, who proposed the first certificateless signcryption scheme. In this paper, we propose a certificateless signcryption scheme in the standard model by using bilinear pairings, which is Type I secure in the original security model of Barbosa and Farshim and can resist the malicious-but-passive key generation center Type II attack. The proposed scheme is proved confidential assuming the modified decisional bilinear Diffie---Hellman (M-DBDH) problem is hard, and unforgeable assuming the square computational Diffie---Hellman (Squ-CDH) problem is hard. At last, we evaluate its efficiency which shows it is of high efficiency.

Searchable public key encryption enables a storage server to retrieve the publicly encrypted data without revealing the original data contents. It offers a perfect cryptographic solution to encrypted data retrieval in encrypted data storage systems. Certificateless cryptography (CLC) is a novel cryptographic primitive that has many merits. It overcomes the key escrow problem in identity-based cryptosystems and the cumbersome certificate problem in conventional public key cryptosystems. Motivated by the appealing features of CLC, three certificateless encryption with keyword search (CLEKS) schemes were presented in the literature. However, all of them were constructed with the costly bilinear pairing and thus are not suitable for the devices that have limited computing resources and battery power. So, it is interesting and worthwhile to design a CLEKS scheme without using bilinear pairing. In this study, we put forward a pairing-free CLEKS scheme that does not exploit bilinear pairing. We strictly prove that the scheme achieves keyword ciphertext indistinguishability against adaptive chosen-keyword attacks under the complexity assumption of the computational Diffie-Hellman problem in the random oracle model. Efficiency comparison and the simulation show that it enjoys better performance than the previous pairing-based CLEKS schemes. In addition, we briefly introduce three extensions of the proposed CLEKS scheme.

Proxy signcryption is a cryptographic primitive which combines the functionalities of a proxy signature scheme and a signcryption scheme. In this paper, based on bilinear pairings, we would like to propose two efficient proxy singcryption schemes. One is certificate based and the other is identity based. Also we analyze the two proposed schemes from efficiency point of view. We show that the certificate based scheme achieves great efficiency in terms of communication cost and computation overhead. And the identity based scheme is much more efficient than the scheme proposed by Li and Chen. What’s more, we also argument that the two proposed schemes are secure in the random oracle model without a secure channel.Keywordsproxy signaturesigncryptionproxy signcryptionbilinear pairings

Internet of Drones (IoD) is considered as a network and management architecture, which can enable unmanned aerial vehicles (UAVs) to collect data in controlled areas and conduct access control for UAVs. However, the current cloud-assisted IoD scheme cannot efficiently achieve secure communication between heterogeneous cryptosystems, and does not support multi-ciphertext equality tests. To improve the security and performance of traditional schemes, we propose a heterogeneous signcryption scheme (HSC-MET) that supports multi-ciphertext equality test. In this paper, we use a multi-ciphertext equality test technique to achieve multi-user simultaneous retrieval of multiple ciphertexts safely and efficiently. In addition, we adopt heterogeneous signcryption technology to realize secure data communication from public key infrastructure (PKI) to certificateless cryptography (CLC). At the same time, the proposed scheme based on the computation without bilinear pairing, which greatly reduces the computational cost. According to the security and performance analysis, under the random oracle model (ROM), the confidentiality, unforgeability and number security of HSC-MET are proved based on the computational Diffie-Hellman (CDH) problem.

A certtificateless signcryption (CLSC) scheme is an important primitive in cryptographic protocols which provides the goals of signing and encryption, simultaneously. In 2010, Liu et al presented the first certificateless signcryption scheme in the standard model, but their scheme is vulnerable against different attacks presented in the literature, till now. In this paper, we will improve their scheme and propose a new certificateless signcryption scheme in the standard model.

In recent years, secure communication and privacy‐preserving are gaining popularity because of the advent of wireless network. Certificateless cryptography (CLC) and identity‐based cryptography (IBC) have already been widely applied in the area of wireless network. Hence, to achieve secure communication from CLC to IBC, we present a heterogeneous signcryption scheme that enables a sender in the CLC to transmit a message to multi‐receiver in the IBC. Our scheme has no restrictions on the system parameters and master keys; private key generator and key generating center generate their own system parameters and master key for the IBC users and the CLC user, separately. Considering privacy‐preserving in heterogeneous communication, we show that our scheme can realize the anonymity of all receivers. Compared with other schemes, our scheme has more advantages, such as public verification and decryption fairness, which are attractive for wireless network applications. Moreover, our scheme has the indistinguishability against adaptive chosen ciphertext attacks, the existential unforgeability against adaptive chosen messages attacks, and anonymous indistinguishability of encryptions under selective‐ID, chosen ciphertext attack in the random oracle model. Copyright © 2016 John Wiley & Sons, Ltd.

This paper designs a secure identity-based threshold signcryption scheme from the bilinear pairings. The construction is based on the recently proposed signcryption scheme of Libert and Quisquater [6]. Our scheme not only has the properties of identity-based and threshold, but also can achieve semantic security under the Decisional Bilinear Diffie-Hellman assumption. It can be proved secure against forgery under chosen message attack in the random oracle model. In the private key distribution protocol, we adopt such method that the private key associated with an identity rather than the master key is shared. In the threshold signcryption phase, we provide a new method to check the malicious members. This is the first identity-based threshold signcryption scheme that can simultaneously achieve both semantic security and others security, such as unforgeability, robustness, and non-repudiation.

Certificateless public key infrastructure (PKI) avoids the key escrow problem associated with identity-based PKI and has recently been widely employed in anonymous communication schemes for vehicular adhoc networks (VANETs). In existing certificateless anonymous signcryption schemes for VANETs, vulnerabilities such as potential attacks involving the substitution of pseudonyms and the forging of pseudonymous public-private key pairs exist due to the lack of “identity-key binding” and “non-linearity processing of public-private key pairs.” To address this issue, we propose an improved certificateless anonymous signcryption scheme based on elliptic curve cryptography. The scheme incorporates bilinear pairing as one of the authentication mechanisms, designs pseudonym generation algorithms and public-private key pair structures, and introduces a pseudonym verification mechanism. The correctness of the scheme is proven under the random oracle model, and its security is extensively demonstrated through detailed discussions on its confidentiality, authentication, unforgeability, anonymity, and traceability. Furthermore, the time and space complexity of the scheme are calculated. By comparing with recently published certificateless signcryption schemes, it is shown that the proposed scheme offers higher security with smaller computational and communication overheads. This certificateless vehicular network signcryption algorithm provides an efficient encryption solution for anonymous communication in vehicular networks, thereby ensuring the rapid development of secure technology for intelligent connected vehicle super terminals.

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Based on mobile devices limitations, several user authentications and key exchange schemes have been proposed for mobile devices using identity-based public key cryptography (ID-PKC). However, these schemes suffer from key escrow problem. Moreover, they are not secure against impersonation attacks, and they can’t achieve perfect forward secrecy. In this paper, a new user authentication and key exchange protocol for the mobile client-server environment is proposed. Certificateless public key cryptography (CL-PKC) and bilinear pairing are adopted in the proposed scheme. Our protocol solves the key escrow problem of identity-based public key cryptography. Also, it is secure against both adversaries type I and type II. Furthermore, the proposed protocol achieves perfect forward secrecy. We prove the security of our protocol in the random oracle model under the Computational Diffie-Hellman (CDH) problem. Hence, the proposed scheme is more suitable for the mobile devices environments.

Since certificateless public key cryptosystem can solve the complex certificate management problem in the traditional public key cryptosystem and the key escrow problem in identity-based cryptosystem and the pairing computation is slower than scalar multiplication over the elliptic curve, how to design certificateless signature (CLS) scheme without bilinear pairings is a challenge. In this paper, we first propose a new pairing-free CLS scheme, and then the security proof is presented in the random oracle model (ROM) under the discrete logarithm assumption. The proposed scheme is more efficient than the previous CLS schemes in terms of computation and communication costs and is more suitable for the applications of low-bandwidth environments.

Wireless sensor networks (WSN) are usually deployed in hostile environments, which having a wide variety of malicious attacks. As various applications of WSN have been proposed, security has become one of the big research challenges dan is receiving increasing attention. In order to insure the security of communication in wireless sensor networks, we proposed a new ID-based signcryption scheme using bilinear pairing. Under the computational Diffie-Hellman assumption, the security of the scheme is proved under the Random Oracle Model. This scheme can be used by the sensor nodes that with low power, less storage space and low computation ability. It is concluded that the proposed lightweight scheme satisfies the security requirements of WSN.

Traditional public key cryptosystem (PKC) requires high maintenance cost for certificate management. Although, identity based cryptosystem (IBC) reduces the overhead of management, it suffers from the drawback of key escrow. Certificate-based cryptosystem solves certificate revocation problem and eliminate third party queries in the traditional PKI. In addition, it also solves the inherent key escrow problem in the IBC. In this paper, we proposed an efficient certificate-based signature and the result shows that the scheme is provable secure against two game attacks of certificate-based signature in the random oracle model. The security is closely related to the difficulty of solving the discrete logarithm problem.